ANSI PWF-2015 PERMANENT WOOD FOUNDATION DESIGN SPECIFICATION WITH COMMENTARY.pdf

1、ANSI/AWC PWF-2015Approval date November 20, 2014PWFPermanent Wood Foundation Design Specificationwith Commentary2015 EDITIONUpdates and ErrataWhile every precaution has been taken toensure the accuracy of this document, errorsmay have occurred during development.Updates or Errata are posted to the A

2、merican Wood Council website at www.awc.org. Technical inquiries may be addressed to infoawc.org.The American Wood Council (AWC) is the voice of North American traditional and engineered wood products. From a renewable resource that absorbs and sequesters carbon, the wood products industry makes pro

3、ducts that are essential to everyday life. AWCs engineers, technologists, scientists, and building code experts develop state-of-the-art engineering data, technology, and standards on structural wood products for use by design professionals, building officials, and wood products manufacturers to ass

4、ure the safe and efficient design and use of wood structural components.AMERICAN WOOD COUNCILiPERMANENT WOOD FOUNDATIONPWFPermanent Wood Foundation Design Specificationwith Commentary2015 EDITIONANSI/AWC PWF-2015Approval date November 20, 2014AMERICAN WOOD COUNCILii PERMANENT WOOD FOUNDATIONPermanen

5、t Wood Foundation Design Specification with Commentary 2015 EditionFirst Web Version: November 2014ISBN: 978-1-940383-03-3Copyright 2014 by American Wood Council All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including, wi

6、thout limitation, electronic, optical, or mechanical means (by way of example and not limitation, photocopying, or recording by or in an information storage retrieval system) without express written permission of the American Wood Council For information on permission to copy material, please contac

7、t:Copyright PermissionAmerican Wood Council222 Catoctin Circle, SE, Suite 201Leesburg, VA 20175infoawc.orgProduced in the United States of AmericaAMERICAN WOOD COUNCILiiiPERMANENT WOOD FOUNDATIONFOREWORD Permanent Wood Foundation (PWF) systems are in-tended for light frame construction including res

8、idential buildings. The realization of full performance potential requires proper attention to design, fabrication, and installation of the foundation. This document primarily addresses structural design requirements.The Permanent Wood Foundation is a load-bearing wood-frame wall and floor system de

9、signed for both above and below-grade use as a foundation for light frame construction. The PWF specifications are based on information developed cooperatively by the wood products industry and the U.S. Forest Service, with the advice and guidance of the Department of Housing and Urban Developments

10、Federal Housing Administration and utilizing research findings of the National Asso-ciation of Home Builders Research Center. The system combines proven construction techniques along with proven below-grade moisture control technology.Stress-graded lumber framing and plywood sheath-ing in the system

11、 shall be engineered to support lateral soil pressures as well as dead, live, snow, wind, and seismic loads. Moisture control measures based on foundation en-gineering, construction practice, and building materials technology are employed to achieve dry and comfort-able living space below-grade. The

12、 most important of these moisture control measures is a granular drainage layer surrounding the lower part of the basement that conducts ground water to a positively drained sump, preventing hydrostatic pressure on the basement walls or floor. Similarly, moisture reaching the upper part of the basem

13、ent foundation wall is deflected downward to the gravel drainage system by polyethylene sheeting, or by the treated plywood wall itself. The result is a dry basement space that is readily insulated and finished for maximum comfort and conservation of energy, utility, and use of space.Wood foundation

14、 sections of lumber framing and plywood sheathing may be factory fabricated or con-structed at the job site.American Wood CouncilAMERICAN WOOD COUNCILiv PERMANENT WOOD FOUNDATIONTABLE OF CONTENTSSection/Title Page Section/Title Page1 GENERAL REQUIREMENTS 11.1 Scope 21.2 Conformance With Standards 21

15、.3 Terminology 21.4 Notation 32 MATERIALS 52.1 Framing 62.2 Sheathing 62.3 Preservative Treatment 62.4 Connections In Preservative-Treated Wood 72.5 Aggregate for Footings and Fill 72.6 Caulking Compound 72.7 Polyethylene Sheeting 72.8 Polyethylene Sheeting Adhesive 83 SOIL: TYPES, STRUCTURAL PERFOR

16、MANCE, DRAINAGE 93.1 Soil Types 103.2 Soil Structure Characteristics 104 ENVIRONMENTAL CONTROL 114.1 Design for Dryness 124.2 Design for Climate Control 135 STRUCTURAL DESIGN . 155.1 General 165.2 Material Design Standards 165.3 Design Loads and Design Methodology 165.4 PWF Wall Design 185.5 Footing

17、 Design 225.6 Basement Floor Design 245.7 Design of Framing Around Openings 24REFERENCES . 25LIST OF FIGURESFigure Page1 PWF Exterior Basement Wall Showing Location of Vapor Barrier With Vented Air Space 132 PWF Exterior Basement Wall Showing Location of Vapor Barrier with no Vented Air Space 143 Pr

18、essure Diagram Used to Calculate Bending Moment, Shear, and Deflection in Foundation Walls with Basement Resisting Lateral Soil Load. . 174 Pressure Diagram Used to Calculate Bending Moment, Shear, and Deflection in Foundation Walls with Crawl Space Resisting Lateral Soil Load. . 175 Basement Wall A

19、nchorage to Resist Wind Uplift. 216 Crawl Space Wall Anchorage to Resist Wind Uplift . 21AMERICAN WOOD COUNCILvPERMANENT WOOD FOUNDATIONCOMMENTARY TABLE OF CONTENTSC1 GENERAL REQUIREMENTS 29C1.1 Scope 29C1.2 Conformance with Standards 29C1.4 Notation 29C2 MATERIALS 30C2.2 Sheathing 30C2.3 Preservati

20、ve Treatment 30C2.5 Aggregate for Footings and Fill 30C3 SOIL: TYPES, STRUCTURAL PERFORMANCE, DRAINAGE 31C3.2 Soil Structural Characteristics 31C4 ENVIRONMENTAL CONTROL 32C4.1 Design for Dryness 32C4.2 Design for Climate Control 32C5 STRUCTURAL DESIGN . 33C5.2 Material Design Standards 33C5.3 Design

21、 Loads and Design Methodology 33C5.4 PWF Wall Design 34C5.5 Footing Design 42C5.6 Basement Floor Design 44REFERENCES . 45Section/Title Page Section/Title PageLIST OF COMMENTARY FIGURESFigure Page Figure PageC4.2.1.2 Insulation of Exterior Walls in Crawl Space Construction. 32C5.3 Typical Loads and R

22、eactions in a Permanent Wood Foundation . 33C5.4-1 Lateral Soil Load Distribution and Reactions for PWF Basement Wall Stud 34C5.4-2 Lateral Soil Load Distribution and Reactions for PWF Basement Wall Stud in Calculating Shear Forces . 34C5.4-3 Calculating Shear at a Section “x” in the PWF Stud . 35C5

23、.4-4 Calculating Bending Moment at a Section “x” in the PWF Stud 36C5.4-5 Lateral Soil Load Distribution and Reactions for PWF Crawl Space Wall Stud 37C5.4-6 Net Lateral Soil Load Distribution and Reactions for PWF Crawl Space Wall Stud 38C5.4-7 Calculating Shear at a Section “x” in the PWF Crawl Sp

24、ace Stud . 38C5.4-8 Shear and Bending Moment for the Portion of Crawl Space PWF Stud Located Above Inside Backfill Height and Subjected to Lateral Forces Due to Outside Backfill Only. 39C5.4-9 Shear and Bending Moment for the Portion of PWF Stud Located Below Inside Backfill Height and Subjected to

25、Lateral Forces Due to Both Outside and Inside Backfill. 39C5.4.4.1 Framing Strap to Transfer Lateral Loads into Floor Joists . 41C5.4.4.2 Concrete Slab to Resist Lateral Forces at the Bottom of a Crawl Space Wall . 41C5.4.5.1 Net Resultant of Forces Due to Differential Backfill Height 42C5.5.2.2-1 P

26、lywood Reinforcing Strip . 42C5.5.2.2-2 Forces on Cantilevered Portion of Footing Plate 43C5.5.3.2-1 Distribution of Axial Load from Wood Footing Plate 43C5.5.3.2-2 Spread Footing using Alternating Layers of Wood Planks 44C5.6.2.2 Blocking for PWF End Walls . 44AMERICAN WOOD COUNCILvi PERMANENT WOOD

27、 FOUNDATIONAMERICAN WOOD COUNCIL1GENERAL REQUIREMENTS1.1 Scope 21.2 Conformance With Standards 21.3 Terminology 21.4 Notation 3PERMANENT WOOD FOUNDATION1AMERICAN WOOD COUNCIL2 GENERAL REQUIREMENTS1.1 ScopeThe basic design and construction requirements for permanent wood foundation (PWF) systems are

28、set forth in this Permanent Wood Foundation Design Specification. Criteria for materials, preservative treatment, soil characteristics, environmental control, design loads, and structural design are included. Where requirements are based on nationally recog-nized standards and specifications, these

29、standards and specifications are referenced without elaboration. This Specification is not intended to preclude the use of materials, assemblies, structures, or designs not meeting the criteria herein, where it is demonstrated by analysis based on recognized theory, full scale or prototype loading t

30、ests, studies of model analogues, or extensive experience in use that the material, assem-bly, structure, or design will perform satisfactorily in its intended use. 1.2 Conformance With Standards The quality of wood products and fasteners, and the design of supporting members and connections shall c

31、omply with the requirements of the building code under which the foundation is designed and the standards specified herein. 1.3 Terminology ALLOWABLE STRESS DESIGN (ASD) . A method of proportioning structural members and their connec-tions such that computed stresses do not exceed speci-fied allowab

32、le stresses when the structure is subjected to appropriate load combinations (also called working stress design). BACKFILL HEIGHT. The height of soil backfill measured from the bottom of the stud to the exterior ground surface at any particular point. For a crawl space with a trenched footing, backf

33、ill height is the difference between exterior and interior ground sur-faces at any particular point. COMPOSITE FOOTING. Footing which is com-prised of a treated wood footing plate and a granular drainage layer consisting of gravel, coarse sand, or crushed stone. DEEP FROST PENETRATION. Frost penetra

34、tions that are typically in the range of 4 feet or greater. END WALL. Exterior PWF wall oriented parallel to floor joists. GRANULAR DRAINAGE LAYER. A continuous layer of gravel, crushed stone or coarse sand used to drain the bottom of the foundation and to distribute the load from the footing to the

35、 soil. JACK STUD. A stud of less than full height that is fastened to a full height stud to support the end of a lintel or beam and to transfer vertical loads to the foot-ing. KNEE WALL. A less than full height wall used out-side the main foundation wall to support brick or stone veneer or other loa

36、ds. LOAD AND RESISTANCE FACTOR DESIGN (LRFD). A method of proportioning structural mem-bers and their connections using load and resistance factors such that no applicable limit state is reached when the structure is subjected to required load com-binations. PLYWOOD. A wood structural panel comprise

37、d of plies of wood veneer arranged in cross-aligned layers. The plies are bonded with an exterior adhesive that cures on application of heat and pressure. SIDE WALL. Exterior PWF wall oriented perpendic-ular to floor joists. SILL. The horizontal member forming the bottom of the rough frame openings

38、of windows. STUB WALL. Relatively short bearing wall null usually approximately 3 ft in height, which is supported by a footing plate and granular drainage layer and provides bearing support for walls and/or floor joists above. PRESERVATIVE-TREATED WOOD. Wood im-pregnated under pressure with preserv

39、atives that re-duce its susceptibility to deterioration. Preservative-treated wood used in permanent wood foundations shall be pressure treated with preservatives in accord-ance with AWPA U1: User Specification for Treated Wood: Commodity Specification A, Section 4.2 Lum-ber and Plywood for Permanen

40、t Wood Foundations; UC4B retention. WALK -OUT BASEMENT. Basement which typical-ly has little or no backfill on one side (walk-out side) and high backfill on the opposite side of the building (or structure). Also referred to as DAYLIGHT base-ment. WOOD FOOTING PLATE. In conjunction with the granular

41、drainage layer, the wood footing plate dis-tributes loads from the PWF wall to the undisturbed soil below. 1.4 Notation IlAMERICAN WOOD COUNCIL3PERMANENT WOOD FOUNDATIONGENERAL REQUIREMENTS1footing plate and granular drainage layer and provides bearing support for walls and/or floor joists above. PR

42、ESERVATIVE-TREATED WOOD. Wood im-pregnated under pressure with preservatives that re-duce its susceptibility to deterioration. Preservative-treated wood used in permanent wood foundations shall be pressure treated with preservatives in accord-ance with AWPA U1: User Specification for Treated Wood: C

43、ommodity Specification A, Section 4.2 Lum-ber and Plywood for Permanent Wood Foundations; UC4B retention. WALK -OUT BASEMENT. Basement which typical-ly has little or no backfill on one side (walk-out side) and high backfill on the opposite side of the building (or structure). Also referred to as DAY

44、LIGHT base-ment. WOOD FOOTING PLATE. In conjunction with the granular drainage layer, the wood footing plate dis-tributes loads from the PWF wall to the undisturbed soil below. 1.4 Notation IlAMERICAN WOOD COUNCIL4 GENERAL REQUIREMENTSAMERICAN WOOD COUNCILMATERIALS25PERMANENT WOOD FOUNDATIONAMERICAN

45、 WOOD COUNCILMATERIALS2.1 Framing 62.2 Sheathing 62.3 Preservative Treatment 62.4 Connections in Preservative-Treated Wood 72.5 Aggregate for Footings and Fill 72.6 Caulking Compound 72.7 Polyethylene Sheeting 72.8 Polyethylene Sheeting Adhesive 8AMERICAN WOOD COUNCIL6 MATERIALS2.1 FramingFraming us

46、ed in the PWF system shall be lumber in accordance with USDOC PS 20 and shall bear the stamp of an approved grading agency or inspection bureau which participates in an accreditation program, such as the American Lumber Standard (ALS) pro-gram or equivalent. 2.2 Sheathing Sheathing used in the PWF s

47、ystem shall be plywood manufactured with all softwood veneers, bonded with exterior adhesive (Exposure 1 or Exteri-or), and grademarked indicating conformance with USDOC PS 1, USDOC PS 2, or applicable code eval-uation reports. 2.3 Preservative Treatment 2.3.1 General All exterior foundation wall fr

48、aming and sheathing (except the upper top plate); all interior bearing wall framing and sheathing, posts or other wood supports used in crawl spaces; all sleepers, joists, blocking and plywood subflooring used in basement floors; and all other plates, framing and sheathing in contact with the ground

49、 or in direct contact with concrete shall be pres-sure treated with preservatives. Treatment shall be in accordance with AWPA U1: Commodity Specification A, Section 4.2 Lumber and Plywood for Permanent Wood Foundations; UC4B Retentions and AWPA T1, Processing and Treatment Standard; Section 8, Special Requirements for Permanent Wood Foundation Mate-rial. Exceptions: 1. Members 8 in. or more above finish grade are not required to be preservative treated. 2. Untreated lumber may be used in interior load-bearing walls where such walls are sup-ported directly on top of a treated f